import math
x1, y1, x2, y2 = map(float, raw_input().split())
print math.sqrt(pow(x2-x1,2) + pow(y2-y1,2)) import math math x1, y1, x2, y2 = map(float, raw_input().split()) x1 map(float, raw_input().split()) map float raw_input().split() ().split () raw_input split y1 x2 y2 print math.sqrt(pow(x2-x1,2) + pow(y2-y1,2)) math.sqrt math sqrt pow(x2-x1,2) + pow(y2-y1,2) pow(x2-x1,2) pow x2-x1 x2 x1 2 pow(y2-y1,2) pow y2-y1 y2 y1 2 y1, x2, y2 = map(float, raw_input().split()) map(float, raw_input().split()) y1 x1, y1, x2, y2 = map(float, raw_input().split()) map(float, raw_input().split()) x1 x2, y2 = map(float, raw_input().split()) map(float, raw_input().split()) x2 y2 = map(float, raw_input().split()) map(float, raw_input().split()) y2
import math
x1, y1, x2, y2 = map(float, raw_input().split())
print math.sqrt(pow(x2-x1,2) + pow(y2-y1,2))
